Blue oxford button down, navy blazer, and a burgundy and navy repp tie. Really, what could be more low key and classic. Someone even told me I had Republican written all over me today. That's a bit severe...no Republican I know where's a gingham square cut from an old shirt.
Aggressive pattern mixing can be tricky, but it's fun when you get the knack. Still, it's a trick best used with reserve. Keep it in your back pocket, and play the purist in between takes. Bold pattern mixing all the time makes you "that guy", just like wearing bow ties too often can make you "that guy". "That guy" likes to turn things up to 11, but "that guy" can be a cartoon. In order to achieve the level of sartorial aplomb that "that guy" achieves when he's at his best, keep the knob at a maximum of 7...most of the time...which is still about five notches higher than most guys these days, anyway.